Antacid tablets, such as tums, are mainly calcium carbonate. calculate the mass of a tums tablet which contains 1000 mg of calcium.

The formula for calcium carbonate is

CaCO3

So each mole of calcium carbonate contains one mole of calcium

Molar mass of calcium carbonate = 100g/mole

Atomic mass of calcium = 40g/ mole

Hence if 40g of calcium is present it means we have 100g of calcium carbonate

if 1 g of calcium is present it means we have 100/ 40 g of calcium carbonate

So if 1000 mg of calcium is present = 100 X 1000 / 40 mg of CaCO3 is present

                                                          = 2500 mg of CaCO3 in tum tablets